Method for reporting channel state in wireless communication system, and apparatus therefor

ABSTRACT

A method for reporting an aperiodic channel state in a wireless communication system according to one embodiment of the present invention, the method being implemented by a terminal, comprises: a step for receiving an aperiodic channel state information (CSI) reporting request from a base station; and a step for calculating aperiodic CSI corresponding to the aperiodic CSI reporting request and transmitting the calculated aperiodic CSI to the base station via an uplink shared channel, wherein if the number of component carriers or CSI processes for the terminal exceeds a specific value, only uplink control information including the aperiodic CSI can be transmitted through the uplink shared channel under specific conditions.

This application is a 35 USC § 371 National Stage entry of InternationalApplication No. PCT/KR2016/001072 filed on Feb. 1, 2016, and claimspriority to U.S. Provisional Application Nos. 62/112,666 filed on Feb.6, 2015; 62/160,567 filed on May 12, 2015; 62/166,706 filed on May 27,2015; 62/204,454 filed on Aug. 13, 2015 and 62/221,104 filed on Sep. 21,2015, all of which are hereby incorporated by reference in theirentireties as if fully set forth herein.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method for reporting a channel state in awireless communication system and an apparatus therefor.

BACKGROUND ART

Recently, various devices requiring machine-to-machine (M2M)communication and high data transfer rate, such as smartphones or tabletpersonal computers (PCs), have appeared and come into widespread use.This has rapidly increased the quantity of data which needs to beprocessed in a cellular network. In order to satisfy such rapidlyincreasing data throughput, recently, carrier aggregation (CA)technology which efficiently uses more frequency bands, cognitive ratiotechnology, multiple antenna (MIMO) technology for increasing datacapacity in a restricted frequency, multiple-base-station cooperativetechnology, etc. have been highlighted. In addition, communicationenvironments have evolved such that the density of accessible nodes isincreased in the vicinity of a user equipment (UE). Here, the nodeincludes one or more antennas and refers to a fixed point capable oftransmitting/receiving radio frequency (RF) signals to/from the userequipment (UE). A communication system including high-density nodes mayprovide a communication service of higher performance to the UE bycooperation between nodes.

A multi-node coordinated communication scheme in which a plurality ofnodes communicates with a user equipment (UE) using the sametime-frequency resources has much higher data throughput than legacycommunication scheme in which each node operates as an independent basestation (BS) to communicate with the UE without cooperation.

A multi-node system performs coordinated communication using a pluralityof nodes, each of which operates as a base station or an access point,an antenna, an antenna group, a remote radio head (RRH), and a remoteradio unit (RRU). Unlike the conventional centralized antenna system inwhich antennas are concentrated at a base station (BS), nodes are spacedapart from each other by a predetermined distance or more in themulti-node system. The nodes can be managed by one or more base stationsor base station controllers which control operations of the nodes orschedule data transmitted/received through the nodes. Each node isconnected to a base station or a base station controller which managesthe node through a cable or a dedicated line.

The multi-node system can be considered as a kind of Multiple InputMultiple Output (MIMO) system since dispersed nodes can communicate witha single UE or multiple UEs by simultaneously transmitting/receivingdifferent data streams. However, since the multi-node system transmitssignals using the dispersed nodes, a transmission area covered by eachantenna is reduced compared to antennas included in the conventionalcentralized antenna system. Accordingly, transmit power required foreach antenna to transmit a signal in the multi-node system can bereduced compared to the conventional centralized antenna system usingMIMO. In addition, a transmission distance between an antenna and a UEis reduced to decrease in pathloss and enable rapid data transmission inthe multi-node system. This can improve transmission capacity and powerefficiency of a cellular system and meet communication performancehaving relatively uniform quality regardless of UE locations in a cell.Further, the multi-node system reduces signal loss generated duringtransmission since base station(s) or base station controller(s)connected to a plurality of nodes transmit/receive data in cooperationwith each other. When nodes spaced apart by over a predetermineddistance perform coordinated communication with a UE, correlation andinterference between antennas are reduced. Therefore, a high signal tointerference-plus-noise ratio (SINR) can be obtained according to themulti-node coordinated communication scheme.

Owing to the above-mentioned advantages of the multi-node system, themulti-node system is used with or replaces the conventional centralizedantenna system to become a new foundation of cellular communication inorder to reduce base station cost and backhaul network maintenance costwhile extending service coverage and improving channel capacity and SINRin next-generation mobile communication systems.

DISCLOSURE Technical Problem

An object of the present invention is to suggest a method for reportinga channel state in a wireless communication system and an operationrelated thereto.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present invention are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present invention could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

In a method for reporting an aperiodic channel state in a wirelesscommunication system according to one embodiment of the presentinvention, the method performed by a terminal, the method comprisesreceiving an aperiodic channel state information (CSI) report requestfrom a base station; and computing aperiodic CSI corresponding to theaperiodic CSI report request and transmitting the computed aperiodic CSIto the base station through an uplink shared channel, wherein when thenumber of component carriers or CSI processes for the terminal exceeds aspecific value, uplink control information only including the aperiodicCSI is transmitted through the uplink shared channel under a predefinedcondition.

Additionally or alternatively, the predefined condition may include acase that downlink control information (DCI) format 0 is used for theaperiodic CSI report request and a modulation and coding scheme fieldvalue included in the DCI is 29.

Additionally or alternatively, the predefined condition may include acase that DCI format 4 is used for the aperiodic CSI report request,only one TB is enabled, a modulation and coding scheme field valueincluded in the DCI is 29, and the number of transmission layers is 1.

Additionally or alternatively, the predefined condition may include acase that a field for the aperiodic CSI report request is N bits, theaperiodic CSI report is triggered, and the number of resource blocks is4 or less, where N may be an integer of 1 or more.

Additionally or alternatively, the predefined condition may include acase that a field for the aperiodic CSI report request is N+1 bits, theaperiodic CSI report is triggered for one serving cell, and the numberof resource blocks is 4 or less, where N may be an integer of 1 or more.

Additionally or alternatively, the predefined condition may include acase that a field for the aperiodic CSI report request is N+1 bits andthe aperiodic CSI report is triggered for a plurality of cells, where Nmay be an integer of 1 or more.

Additionally or alternatively, the predefined condition may include acase that a field for the aperiodic CSI report request is N+1 bits, theaperiodic CSI report is triggered for one CSI process and the number ofresource blocks is 4 or less, where N may be an integer of 1 or more.

Additionally or alternatively, the predefined condition may include acase that a field for the aperiodic CSI report request is N+1 bits andthe aperiodic CSI report is triggered for a plurality of CSI processes,where N may be an integer of 1 or more.

Additionally or alternatively, the predefined condition may include acase that a field for the aperiodic CSI report request is N+1 bits, theaperiodic CSI report is triggered for a plurality of cells or CSIprocesses, and the number of resource blocks is r or less, where N maybe an integer of 1 or more.

Additionally or alternatively, the r may be determined in proportionalto a maximum value of the number of all cells or CSI processesconfigured for the terminal, the number of cells or CSI processesassociated with a value indicated by the aperiodic CSI report request,or the number of cells or CSI processes associated with each value of aDCI field for the aperiodic CSI report request.

Additionally or alternatively, the r may be determined dynamically inproportional to the number of cells or CSI processes associated with avalue indicated by the aperiodic CSI report request.

Additionally or alternatively, a modulation order for the aperiodic CSImay be determined in accordance with at least one parameter related toDCI for the aperiodic CSI report request.

Additionally or alternatively, the modulation order for the aperiodicCSI may be determined in accordance with a resource size allocated forthe uplink shared channel.

Additionally or alternatively, the modulation order for the aperiodicCSI may be determined in accordance with combination of the number ofcomponent carriers or CSI processes for the aperiodic CSI and a resourcesize allocated for the uplink shared channel.

Additionally or alternatively, the modulation order for the aperiodicCSI may be determined in accordance with combination of a size of theaperiodic CSI and a resource size allocated for the uplink sharedchannel.

Additionally or alternatively, the modulation order for the aperiodicCSI may be determined in accordance with the number of transmissionlayers included in DCI for the aperiodic CSI report request.

Additionally or alternatively, the modulation order for the aperiodicCSI may be determined in accordance with a format of DCI for theaperiodic CSI report request.

Additionally or alternatively, the modulation order for the aperiodicCSI may be determined in accordance with the number of bits of a fieldfor the aperiodic CSI report request.

Additionally or alternatively, the modulation order for the aperiodicCSI may be determined in accordance with a bit value of a field for theaperiodic CSI report request.

A terminal configured to report an aperiodic channel state in a wirelesscommunication system according to one embodiment of the presentinvention comprises a radio frequency (RF) unit; and a processorcontrols the RF unit, wherein the processor receives an aperiodicchannel state information (CSI) report request from a base station andcompute aperiodic CSI corresponding to the aperiodic CSI report requestand transmits the computed aperiodic CSI to the base station through anuplink shared channel, and wherein when the number of component carriersor CSI processes for the terminal exceeds a specific value, uplinkcontrol information only including the aperiodic CSI may be transmittedthrough the uplink shared channel under a predefined condition.

The above technical solutions are merely some parts of the embodimentsof the present invention and various embodiments into which thetechnical features of the present invention are incorporated can bederived and understood by persons skilled in the art from the followingdetailed description of the present invention.

Advantageous Effects

According to one embodiment of the present invention, a channel statemay efficiently be reported in a wireless communication system.

It will be appreciated by persons skilled in the art that that theeffects that can be achieved through the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is diagram illustrating an example of a radio frame structureused in a wireless communication system;

FIG. 2 is diagram illustrating an example of a downlink/uplink (DL/UL)slot structure in a wireless communication system;

FIG. 3 is diagram illustrating an example of a downlink (DL) subframestructure used in a 3GPP LTE/LTE-A system;

FIG. 4 is diagram illustrating an example of an uplink (UL) subframestructure used in a 3GPP LTE/LTE-A system;

FIG. 5 is a diagram illustrating an operation according to oneembodiment of the present invention; and

FIG. 6 is a block diagram illustrating an apparatus for implementing theembodiment(s) of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The accompanying drawings illustrate exemplary embodiments ofthe present invention and provide a more detailed description of thepresent invention. However, the scope of the present invention shouldnot be limited thereto.

In some cases, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

In the present invention, a user equipment (UE) is fixed or mobile. TheUE is a device that transmits and receives user data and/or controlinformation by communicating with a base station (BS). The term ‘UE’ maybe replaced with ‘terminal equipment’, ‘Mobile Station (MS)’, ‘MobileTerminal (MT)’, ‘User Terminal (UT)’, ‘Subscriber Station (SS)’,‘wireless device’, ‘Personal Digital Assistant (PDA)’, ‘wireless modem’,‘handheld device’, etc. A BS is typically a fixed station thatcommunicates with a UE and/or another BS. The BS exchanges data andcontrol information with a UE and another BS. The term ‘BS’ may bereplaced with ‘Advanced Base Station (ABS)’, ‘Node B’, ‘evolved-Node B(eNB)’, ‘Base Transceiver System (BTS)’, ‘Access Point (AP)’,‘Processing Server (PS)’, etc. In the following description, BS iscommonly called eNB.

In the present invention, a node refers to a fixed point capable oftransmitting/receiving a radio signal to/from a UE by communication withthe UE. Various eNBs can be used as nodes. For example, a node can be aBS, NB, eNB, pico-cell eNB (PeNB), home eNB (HeNB), relay, repeater,etc. Furthermore, a node may not be an eNB. For example, a node can be aradio remote head (RRH) or a radio remote unit (RRU). The RRH and RRUhave power levels lower than that of the eNB. Since the RRH or RRU(referred to as RRH/RRU hereinafter) is connected to an eNB through adedicated line such as an optical cable in general, cooperativecommunication according to RRH/RRU and eNB can be smoothly performedcompared to cooperative communication according to eNBs connectedthrough a wireless link. At least one antenna is installed per node. Anantenna may refer to an antenna port, a virtual antenna or an antennagroup. A node may also be called a point. Unlike a conventionalcentralized antenna system (CAS) (i.e. single node system) in whichantennas are concentrated in an eNB and controlled an eNB controller,plural nodes are spaced apart at a predetermined distance or longer in amulti-node system. The plural nodes can be managed by one or more eNBsor eNB controllers that control operations of the nodes or schedule datato be transmitted/received through the nodes. Each node may be connectedto an eNB or eNB controller managing the corresponding node via a cableor a dedicated line. In the multi-node system, the same cell identity(ID) or different cell IDs may be used for signal transmission/receptionthrough plural nodes. When plural nodes have the same cell ID, each ofthe plural nodes operates as an antenna group of a cell. If nodes havedifferent cell IDs in the multi-node system, the multi-node system canbe regarded as a multi-cell (e.g., macro-cell/femto-cell/pico-cell)system. When multiple cells respectively configured by plural nodes areoverlaid according to coverage, a network configured by multiple cellsis called a multi-tier network. The cell ID of the RRH/RRU may beidentical to or different from the cell ID of an eNB. When the RRH/RRUand eNB use different cell IDs, both the RRH/RRU and eNB operate asindependent eNBs.

In a multi-node system according to the present invention, which will bedescribed below, one or more eNBs or eNB controllers connected to pluralnodes can control the plural nodes such that signals are simultaneouslytransmitted to or received from a UE through some or all nodes. Whilethere is a difference between multi-node systems according to the natureof each node and implementation form of each node, multi-node systemsare discriminated from single node systems (e.g. CAS, conventional MIMOsystems, conventional relay systems, conventional repeater systems,etc.) since a plurality of nodes provides communication services to a UEin a predetermined time-frequency resource. Accordingly, embodiments ofthe present invention with respect to a method of performing coordinateddata transmission using some or all nodes can be applied to varioustypes of multi-node systems. For example, a node refers to an antennagroup spaced apart from another node by a predetermined distance ormore, in general. However, embodiments of the present invention, whichwill be described below, can even be applied to a case in which a noderefers to an arbitrary antenna group irrespective of node interval. Inthe case of an eNB including an X-pole (cross polarized) antenna, forexample, the embodiments of the preset invention are applicable on theassumption that the eNB controls a node composed of an H-pole antennaand a V-pole antenna.

A communication scheme through which signals are transmitted/receivedvia plural transmit (Tx)/receive (Rx) nodes, signals aretransmitted/received via at least one node selected from plural Tx/Rxnodes, or a node transmitting a downlink signal is discriminated from anode transmitting an uplink signal is called multi-eNB MIMO or CoMP(Coordinated Multi-Point Tx/Rx). Coordinated transmission schemes fromamong CoMP communication schemes can be categorized into JP (JointProcessing) and scheduling coordination. The former may be divided intoJT (Joint Transmission)/JR (Joint Reception) and DPS (Dynamic PointSelection) and the latter may be divided into CS (CoordinatedScheduling) and CB (Coordinated Beamforming). DPS may be called DCS(Dynamic Cell Selection). When JP is performed, more variouscommunication environments can be generated, compared to other CoMPschemes. JT refers to a communication scheme by which plural nodestransmit the same stream to a UE and JR refers to a communication schemeby which plural nodes receive the same stream from the UE. The UE/eNBcombine signals received from the plural nodes to restore the stream. Inthe case of JT/JR, signal transmission reliability can be improvedaccording to transmit diversity since the same stream is transmittedfrom/to plural nodes. DPS refers to a communication scheme by which asignal is transmitted/received through a node selected from plural nodesaccording to a specific rule. In the case of DPS, signal transmissionreliability can be improved because a node having a good channel statebetween the node and a UE is selected as a communication node.

In the present invention, a cell refers to a specific geographical areain which one or more nodes provide communication services. Accordingly,communication with a specific cell may mean communication with an eNB ora node providing communication services to the specific cell. Adownlink/uplink signal of a specific cell refers to a downlink/uplinksignal from/to an eNB or a node providing communication services to thespecific cell. A cell providing uplink/downlink communication servicesto a UE is called a serving cell. Furthermore, channel status/quality ofa specific cell refers to channel status/quality of a channel or acommunication link generated between an eNB or a node providingcommunication services to the specific cell and a UE. In 3GPP LTE-Asystems, a UE can measure downlink channel state from a specific nodeusing one or more CSI-RSs (Channel State Information Reference Signals)transmitted through antenna port(s) of the specific node on a CSI-RSresource allocated to the specific node. In general, neighboring nodestransmit CSI-RS resources on orthogonal CSI-RS resources. When CSI-RSresources are orthogonal, this means that the CSI-RS resources havedifferent subframe configurations and/or CSI-RS sequences which specifysubframes to which CSI-RSs are allocated according to CSI-RS resourceconfigurations, subframe offsets and transmission periods, etc. whichspecify symbols and subcarriers carrying the CSI RSs.

In the present invention, PDCCH (Physical Downlink ControlChannel)/PCFICH (Physical Control Format Indicator Channel)/PHICH(Physical Hybrid automatic repeat request Indicator Channel)/PDSCH(Physical Downlink Shared Channel) refer to a set of time-frequencyresources or resource elements respectively carrying DCI (DownlinkControl Information)/CFI (Control Format Indicator)/downlink ACK/NACK(Acknowledgement/Negative ACK)/downlink data. In addition, PUCCH(Physical Uplink Control Channel)/PUSCH (Physical Uplink SharedChannel)/PRACH (Physical Random Access Channel) refer to sets oftime-frequency resources or resource elements respectively carrying UCI(Uplink Control Information)/uplink data/random access signals. In thepresent invention, a time-frequency resource or a resource element (RE),which is allocated to or belongs toPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH, is referred to as aPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE orPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource. In the followingdescription, transmission of PUCCH/PUSCH/PRACH by a UE is equivalent totransmission of uplink control information/uplink data/random accesssignal through or on PUCCH/PUSCH/PRACH. Furthermore, transmission ofPDCCH/PCFICH/PHICH/PDSCH by an eNB is equivalent to transmission ofdownlink data/control information through or onPDCCH/PCFICH/PHICH/PDSCH.

FIG. 1 illustrates an exemplary radio frame structure used in a wirelesscommunication system. FIG. 1(a) illustrates a frame structure forfrequency division duplex (FDD) used in 3GPP LTE/LTE-A and FIG. 1(b)illustrates a frame structure for time division duplex (TDD) used in3GPP LTE/LTE-A.

Referring to FIG. 1, a radio frame used in 3GPP LTE/LTE-A has a lengthof 10 ms (307200Ts) and includes 10 subframes in equal size. The 10subframes in the radio frame may be numbered. Here, Ts denotes samplingtime and is represented as Ts=1/(2048*15 kHz). Each subframe has alength of 1 ms and includes two slots. 20 slots in the radio frame canbe sequentially numbered from 0 to 19. Each slot has a length of 0.5 ms.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources can be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame can be configured differently according to duplex mode.Downlink transmission is discriminated from uplink transmission byfrequency in FDD mode, and thus the radio frame includes only one of adownlink subframe and an uplink subframe in a specific frequency band.In TDD mode, downlink transmission is discriminated from uplinktransmission by time, and thus the radio frame includes both a downlinksubframe and an uplink subframe in a specific frequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink- DL-UL to-Uplink configu- Switch-point Subframe numberration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5 msD S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms D S U U U D D D DD 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D D D D 6 5 ms D S U UU D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes threefields of DwPTS (Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS(Uplink Pilot TimeSlot). DwPTS is a period reserved for downlinktransmission and UpPTS is a period reserved for uplink transmission.Table 2 shows special subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special Normal Extended Normal Extended subframecyclic prefix cyclic prefix cyclic prefix cyclic prefix configurationDwPTS in uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) 2192· T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 ·T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600· T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592· T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 ·T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — — 9 13168 ·T_(s) — — —

FIG. 2 illustrates an exemplary downlink/uplink slot structure in awireless communication system. Particularly, FIG. 2 illustrates aresource grid structure in 3GPP LTE/LTE-A. A resource grid is presentper antenna port.

Referring to FIG. 2, a slot includes a plurality of OFDM (OrthogonalFrequency Division Multiplexing) symbols in the time domain and aplurality of resource blocks (RBs) in the frequency domain. An OFDMsymbol may refer to a symbol period. A signal transmitted in each slotmay be represented by a resource grid composed of N_(RB) ^(DL/UL)*N_(sc)^(RB) subcarriers and N_(symb) ^(DL/UL) OFDM symbols. Here, N_(RB) ^(DL)denotes the number of RBs in a downlink slot and N_(RB) ^(UL) denotesthe number of RBs in an uplink slot. N_(RB) ^(DL) and N_(RB) ^(UL)respectively depend on a DL transmission bandwidth and a UL transmissionbandwidth. N_(symb) ^(DL) denotes the number of OFDM symbols in thedownlink slot and N_(symb) ^(UL) denotes the number of OFDM symbols inthe uplink slot. In addition, N_(sc) ^(RB) denotes the number ofsubcarriers constructing one RB.

An OFDM symbol may be called an SC-FDM (Single Carrier FrequencyDivision Multiplexing) symbol according to multiple access scheme. Thenumber of OFDM symbols included in a slot may depend on a channelbandwidth and the length of a cyclic prefix (CP). For example, a slotincludes 7 OFDM symbols in the case of normal CP and 6 OFDM symbols inthe case of extended CP. While FIG. 2 illustrates a subframe in which aslot includes 7 OFDM symbols for convenience, embodiments of the presentinvention can be equally applied to subframes having different numbersof OFDM symbols. Referring to FIG. 2, each OFDM symbol includes N_(RB)^(DL/UL)*N_(sc) ^(RB) subcarriers in the frequency domain. Subcarriertypes can be classified into a data subcarrier for data transmission, areference signal subcarrier for reference signal transmission, and nullsubcarriers for a guard band and a direct current (DC) component. Thenull subcarrier for a DC component is a subcarrier remaining unused andis mapped to a carrier frequency (f0) during OFDM signal generation orfrequency up-conversion. The carrier frequency is also called a centerfrequency.

An RB is defined by N_(symb) ^(DL/UL) (e.g., 7) consecutive OFDM symbolsin the time domain and N_(sc) ^(RB) (e.g., 12) consecutive subcarriersin the frequency domain. For reference, a resource composed by an OFDMsymbol and a subcarrier is called a resource element (RE) or a tone.Accordingly, an RB is composed of N_(symb) ^(DL/UL)*N_(sc) ^(RB) REs.Each RE in a resource grid can be uniquely defined by an index pair(k, 1) in a slot. Here, k is an index in the range of 0 to N_(symb)^(DL/UL)*N_(sc) ^(RB)−1 in the frequency domain and 1 is an index in therange of 0 to N_(symb) ^(DL/UL)−1.

Two RBs that occupy N_(sc) ^(RB) consecutive subcarriers in a subframeand respectively disposed in two slots of the subframe are called aphysical resource block (PRB) pair. Two RBs constituting a PRB pair havethe same PRB number (or PRB index). A virtual resource block (VRB) is alogical resource allocation unit for resource allocation. The VRB hasthe same size as that of the PRB. The VRB may be divided into alocalized VRB and a distributed VRB depending on a mapping scheme of VRBinto PRB. The localized VRBs are mapped into the PRBs, whereby VRBnumber (VRB index) corresponds to PRB number. That is, nPRB=nVRB isobtained. Numbers are given to the localized VRBs from 0 to N_(VRB)^(DL)−1, and N_(VRB) ^(DL)=N_(RB) ^(DL) is obtained. Accordingly,according to the localized mapping scheme, the VRBs having the same VRBnumber are mapped into the PRBs having the same PRB number at the firstslot and the second slot. On the other hand, the distributed VRBs aremapped into the PRBs through interleaving. Accordingly, the VRBs havingthe same VRB number may be mapped into the PRBs having different PRBnumbers at the first slot and the second slot. Two PRBs, which arerespectively located at two slots of the subframe and have the same VRBnumber, will be referred to as a pair of VRBs.

FIG. 3 illustrates a downlink (DL) subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 3, a DL subframe is divided into a control region anda data region. A maximum of three (four) OFDM symbols located in a frontportion of a first slot within a subframe correspond to the controlregion to which a control channel is allocated. A resource regionavailable for PDCCH transmission in the DL subframe is referred to as aPDCCH region hereinafter. The remaining OFDM symbols correspond to thedata region to which a physical downlink shared chancel (PDSCH) isallocated. A resource region available for PDSCH transmission in the DLsubframe is referred to as a PDSCH region hereinafter. Examples ofdownlink control channels used in 3GPP LTE include a physical controlformat indicator channel (PCFICH), a physical downlink control channel(PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc. ThePCFICH is transmitted at a first OFDM symbol of a subframe and carriesinformation regarding the number of OFDM symbols used for transmissionof control channels within the subframe. The PHICH is a response ofuplink transmission and carries an HARQ acknowledgment (ACK)/negativeacknowledgment (NACK) signal.

Control information carried on the PDCCH is called downlink controlinformation (DCI). The DCI contains resource allocation information andcontrol information for a UE or a UE group. For example, the DCIincludes a transport format and resource allocation information of adownlink shared channel (DL-SCH), a transport format and resourceallocation information of an uplink shared channel (UL-SCH), paginginformation of a paging channel (PCH), system information on the DL-SCH,information about resource allocation of an upper layer control messagesuch as a random access response transmitted on the PDSCH, a transmitcontrol command set with respect to individual UEs in a UE group, atransmit power control command, information on activation of a voiceover IP (VoIP), downlink assignment index (DAI), etc. The transportformat and resource allocation information of the DL-SCH are also calledDL scheduling information or a DL grant and the transport format andresource allocation information of the UL-SCH are also called ULscheduling information or a UL grant. The size and purpose of DCIcarried on a PDCCH depend on DCI format and the size thereof may bevaried according to coding rate. Various formats, for example, formats 0and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3 and 3Afor downlink, have been defined in 3GPP LTE. Control information such asa hopping flag, information on RB allocation, modulation coding scheme(MCS), redundancy version (RV), new data indicator (NDI), information ontransmit power control (TPC), cyclic shift demodulation reference signal(DMRS), UL index, channel quality information (CQI) request, DLassignment index, HARQ process number, transmitted precoding matrixindicator (TPMI), precoding matrix indicator (PMI), etc. is selected andcombined based on DCI format and transmitted to a UE as DCI.

In general, a DCI format for a UE depends on transmission mode (TM) setfor the UE. In other words, only a DCI format corresponding to aspecific TM can be used for a UE configured in the specific TM.

A PDCCH is transmitted on an aggregation of one or several consecutivecontrol channel elements (CCEs). The CCE is a logical allocation unitused to provide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). For example, a CCE corresponds to 9 REGs and an REG correspondsto 4 REs. 3GPP LTE defines a CCE set in which a PDCCH can be located foreach UE. A CCE set from which a UE can detect a PDCCH thereof is calleda PDCCH search space, simply, search space. An individual resourcethrough which the PDCCH can be transmitted within the search space iscalled a PDCCH candidate. A set of PDCCH candidates to be monitored bythe UE is defined as the search space. In 3GPP LTE/LTE-A, search spacesfor DCI formats may have different sizes and include a dedicated searchspace and a common search space. The dedicated search space is aUE-specific search space and is configured for each UE. The commonsearch space is configured for a plurality of UEs. Aggregation levelsdefining the search space is as follows.

TABLE 3 Number of Search Space PDCCH Aggregation Size [in candidatesType Level L CCEs] M^((L)) UE- 1 6 6 specific 2 12 6 4 8 2 8 16 2 Common4 16 4 8 16 2

A PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to CCEaggregation level. An eNB transmits a PDCCH (DCI) on an arbitrary PDCCHcandidate with in a search space and a UE monitors the search space todetect the PDCCH (DCI). Here, monitoring refers to attempting to decodeeach PDCCH in the corresponding search space according to all monitoredDCI formats. The UE can detect the PDCCH thereof by monitoring pluralPDCCHs. Since the UE does not know the position in which the PDCCHthereof is transmitted, the UE attempts to decode all PDCCHs of thecorresponding DCI format for each subframe until a PDCCH having the IDthereof is detected. This process is called blind detection (or blinddecoding (BD)).

The eNB can transmit data for a UE or a UE group through the dataregion. Data transmitted through the data region may be called userdata. For transmission of the user data, a physical downlink sharedchannel (PDSCH) may be allocated to the data region. A paging channel(PCH) and downlink-shared channel (DL-SCH) are transmitted through thePDSCH. The UE can read data transmitted through the PDSCH by decodingcontrol information transmitted through a PDCCH. Informationrepresenting a UE or a UE group to which data on the PDSCH istransmitted, how the UE or UE group receives and decodes the PDSCH data,etc. is included in the PDCCH and transmitted. For example, if aspecific PDCCH is CRC (cyclic redundancy check)-masked having radionetwork temporary identify (RNTI) of “A” and information about datatransmitted using a radio resource (e.g., frequency position) of “B” andtransmission format information (e.g., transport block size, modulationscheme, coding information, etc.) of “C” is transmitted through aspecific DL subframe, the UE monitors PDCCHs using RNTI information anda UE having the RNTI of “A” detects a PDCCH and receives a PDSCHindicated by “B” and “C” using information about the PDCCH.

A reference signal (RS) to be compared with a data signal is necessaryfor the UE to demodulate a signal received from the eNB. A referencesignal refers to a predetermined signal having a specific waveform,which is transmitted from the eNB to the UE or from the UE to the eNBand known to both the eNB and UE. The reference signal is also called apilot. Reference signals are categorized into a cell-specific RS sharedby all UEs in a cell and a modulation RS (DM RS) dedicated for aspecific UE. A DM RS transmitted by the eNB for demodulation of downlinkdata for a specific UE is called a UE-specific RS. Both or one of DM RSand CRS may be transmitted on downlink. When only the DM RS istransmitted without CRS, an RS for channel measurement needs to beadditionally provided because the DM RS transmitted using the sameprecoder as used for data can be used for demodulation only. Forexample, in 3GPP LTE(-A), CSI-RS corresponding to an additional RS formeasurement is transmitted to the UE such that the UE can measurechannel state information. CSI-RS is transmitted in each transmissionperiod corresponding to a plurality of subframes based on the fact thatchannel state variation with time is not large, unlike CRS transmittedper subframe.

FIG. 4 illustrates an exemplary uplink subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 4, a UL subframe can be divided into a control regionand a data region in the frequency domain. One or more PUCCHs (physicaluplink control channels) can be allocated to the control region to carryuplink control information (UCI). One or more PUSCHs (Physical uplinkshared channels) may be allocated to the data region of the UL subframeto carry user data.

In the UL subframe, subcarriers spaced apart from a DC subcarrier areused as the control region. In other words, subcarriers corresponding toboth ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a component remaining unused forsignal transmission and is mapped to the carrier frequency f0 duringfrequency up-conversion. A PUCCH for a UE is allocated to an RB pairbelonging to resources operating at a carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots.Assignment of the PUCCH in this manner is represented as frequencyhopping of an RB pair allocated to the PUCCH at a slot boundary. Whenfrequency hopping is not applied, the RB pair occupies the samesubcarrier.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response signal to a downlink data        packet on a PDSCH and indicates whether the downlink data packet        has been successfully received. A 1-bit ACK/NACK signal is        transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords. HARQ-ACK responses include positive ACK        (ACK), negative ACK (NACK), discontinuous transmission (DTX) and        NACK/DTX. Here, the term HARQ-ACK is used interchangeably with        the term HARQ ACK/NACK and ACK/NACK.    -   Channel State Indicator (CSI): This is feedback information        about a downlink channel. Feedback information regarding MIMO        includes a rank indicator (RI) and a precoding matrix indicator        (PMI).

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a soundingreference signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports various formats according toinformation transmitted thereon.

Table 4 shows the mapping relationship between PUCCH formats and UCI inLTE/LTE-A.

TABLE 4 Number of bits per PUCCH Modulation subframe, format schemeM_(bit) Usage Etc. 1 N/A N/A SR (Scheduling Request) 1a BPSK 1 ACK/NACKor One SR + ACK/NACK codeword 1b QPSK 2 ACK/NACK or Two SR + ACK/NACKcodeword 2 QPSK 20 CQI/PMI/RI Joint coding ACK/NACK (extended CP) 2aQPSK + BPSK 21 CQI/PMI/RI + Normal CP ACK/NACK only 2b QPSK + QPSK 22CQI/PMI/RI + Normal CP ACK/NACK only 3 QPSK 48 ACK/NACK or SR + ACK/NACKor CQI/PMI/RI + ACK/NACK

Referring to Table 4, PUCCH formats 1/1a/1b are used to transmitACK/NACK information, PUCCH format 2/2a/2b are used to carry CSI such asCQI/PMI/RI and PUCCH format 3 is used to transmit ACK/NACK information.

CSI Reporting

In the 3GPP LTE(-A) system, a user equipment (UE) is defined to reportCSI to a BS. Herein, the CSI collectively refers to informationindicating the quality of a radio channel (also called a link) createdbetween a UE and an antenna port. The CSI includes, for example, a rankindicator (RI), a precoding matrix indicator (PMI), and a channelquality indicator (CQI). Herein, the RI, which indicates rankinformation about a channel, refers to the number of streams that a UEreceives through the same time-frequency resource. The RI value isdetermined depending on long-term fading of the channel, and is thususually fed back to the BS by the UE with a longer period than for thePMI and CQI. The PMI, which has a value reflecting the channel spaceproperty, indicates a precoding index preferred by the UE based on ametric such as SINR. The CQI, which has a value indicating the intensityof a channel, typically refers to a receive SINR which may be obtainedby the BS when the PMI is used.

The UE calculates, based on measurement of the radio channel, apreferred PMI and RI from which an optimum or highest transmission ratemay be derived when used by the BS in the current channel state, andfeeds back the calculated PMI and RI to the BS. Herein, the CQI refersto a modulation and coding scheme providing an acceptable packet errorprobability for the PMI/RI that is fed back.

In the LTE-A system which is expected to include more precise MU-MIMOand explicit CoMP operations, current CSI feedback is defined in LTE,and thus new operations to be introduced may not be sufficientlysupported. As requirements for CSI feedback accuracy for obtainingsufficient MU-MIMO or CoMP throughput gain became complicated, it hasbeen agreed that the PMI should be configured with a long term/widebandPMI (W₁) and a short term/subband PMI (W₂). In other words, the finalPMI is expressed as a function of W₁ and W₂. For example, the final PMIW may be defined as follows: W=W₁*W₂ or W=W₂*W₁. Accordingly, in LTE-A,the CSI may include RI, W₁, W₂ and CQI.

In the 3GPP LTE(-A) system, an uplink channel used for CSI transmissionis configured as shown in Table 5.

TABLE 5 Aperiodic Scheduling scheme Periodic CSI transmission CSItransmission Frequency non-selective PUCCH — Frequency selective PUCCHPUSCH

Referring to Table 5, CSI may be transmitted with a periodicity definedin a higher layer, using a physical uplink control channel (PUCCH). Whenneeded by the scheduler, a physical uplink shared channel (PUSCH) may beaperiodically used to transmit the CSI. Transmission of the CSI over thePUSCH is possible only in the case of frequency selective scheduling andaperiodic CSI transmission. Hereinafter, CSI transmission schemesaccording to scheduling schemes and periodicity will be described.

1) Transmitting the CQI/PMIRI over the PUSCH after receiving a CSItransmission request control signal (a CSI request)

A PUSCH scheduling control signal (UL grant) transmitted over a PDCCHmay include a control signal for requesting transmission of CSI. Thetable below shows modes of the UE in which the CQI, PMI and RI aretransmitted over the PUSCH.

TABLE 6 PMI Feedback Type No PMI Single PMI Multiple PMIs PUSCH CQIFeedback Type Wideband Mode 1-2 (Wideband CQI) RI 1st wideband CQI (4bit) 2nd wideband CQI (4 bit) if RI >1 N * Subband PMI (4 bit) (N is thetotal # of subbands) (if 8Tx Ant, N * subband W2 + wideband W1) UEselected Mode 2-0 Mode 2-2 (Subband CQI) RI (only for Open- RI loop SM)1st wideband 1st wideband CQI (4 bit) + Best-M CQI (4 bit) + Best-M CQI(2 bit) CQI (2 bit) 2nd wideband (Best-M CQI: An CQI (4 bit) + Best-Maverage CQI for M CQI (2 bit) if RI >1 SBs selected from Best-M index (Lamong N SBs) bit) Best-M index (L Wideband bit) PMI (4 bit) + Best-M PMI(4 bit) (if 8Tx Ant, wideband W2 + Best-M W2 + wideband W1) HigherLayer- Mode 3-0 Mode 3-1 Mode 3-2 configured RI (only for Open- RI RI(Subband CQI) loop SM) 1st wideband 1st wideband 1st wideband CQI (4bit) + CQI (4 bit) + CQI (4 bit) + N * subband N * subbandCQI (2 bit)N * subbandCQI (2 bit) CQI (2 bit) 2nd wideband 2nd wideband CQI (4bit) + CQI (4 bit) + N * subbandCQI (2 bit) N * subbandCQI (2 bit) ifRI >1 if RI >1 Wideband N * Subband PMI (4 bit) PMI (4 bit) (if 8Tx Ant,(N is the total # of wideband W2 + subbands) wideband W1) (if 8Tx Ant,N * subband W2 + wideband W1)

The transmission modes in Table 6 are selected in a higher layer, andthe CQI/PMI/RI are all transmitted in a PUSCH subframe. Hereinafter,uplink transmission methods for the UE according to the respective modeswill be described.

Mode 1-2 represents a case where precoding matrices are selected on theassumption that data is transmitted only in subbands. The UE generates aCQI on the assumption of a precoding matrix selected for a system bandor a whole band (set S) designated in a higher layer. In Mode 1-2, theUE may transmit a CQI and a PMI value for each subband. Herein, the sizeof each subband may depend on the size of the system band.

A UE in Mode 2-0 may select M preferred subbands for a system band or aband (set S) designated in a higher layer. The UE may generate one CQIvalue on the assumption that data is transmitted for the M selectedsubbands. Preferably, the UE additionally reports one CQI (wideband CQI)value for the system band or set S. If there are multiple codewords forthe M selected subbands, the UE defines a CQI value for each codeword ina differential form.

In this case, the differential CQI value is determined as a differencebetween an index corresponding to the CQI value for the M selectedsubbands and a wideband (WB) CQI index.

The UE in Mode 2-0 may transmit, to a BS, information about thepositions of the M selected subbands, one CQI value for the M selectedsubbands and a CQI value generated for the whole band or designated band(set S). Herein, the size of a subband and the value of M may depend onthe size of the system band.

A UE in Mode 2-2 may select positions of M preferred subbands and asingle precoding matrix for the M preferred subbands simultaneously onthe assumption that data is transmitted through the M preferredsubbands. Herein, a CQI value for the M preferred subbands is definedfor each codeword. In addition, the UE additionally generates a widebandCQI value for the system band or a designated band (set S).

The UE in Mode 2-2 may transmit, to the BS, information about thepositions of the M preferred subbands, one CQI value for the M selectedsubbands and a single PMI for the M preferred subbands, a wideband PMI,and a wideband CQI value. Herein, the size of a subband and the value ofM may depend on the size of the system band.

A UE in Mode 3-0 generates a wideband CQI value. The UE generates a CQIvalue for each subband on the assumption that data is transmittedthrough each subband. In this case, even if RI>1, the CQI valuerepresents only the CQI value for the first codeword.

A UE in Mode 3-1 generates a single precoding matrix for the system bandor a designated band (set S). The UE generates a CQI subband for eachcodeword on the assumption of the single precoding matrix generated foreach subband. In addition, the UE may generate a wideband CQI on theassumption of the single precoding matrix. The CQI value for eachsubband may be expressed in a differential form. The subband CQI valueis calculated as a difference between the subband CQI index and thewideband CQI index. Herein, the size of each subband may depend on thesize of the system band.

A UE in Mode 3-2 generates a precoding matrix for each subband in placeof a single precoding matrix for the whole band, in contrast with the UEin Mode 3-1.

2) Periodic CQI/PMI/RI Transmission Over PUCCH

The UE may periodically transmit CSI (e.g., CQI/PMI/PTI (precoding typeindicator) and/or RI information) to the BS over a PUCCH. If the UEreceives a control signal instructing transmission of user data, the UEmay transmit a CQI over the PUCCH. Even if the control signal istransmitted over a PUSCH, the CQI/PMI/PTI/RI may be transmitted in oneof the modes defined in the following table.

TABLE 7 PMI feedback type No PMI Single PMI PUCCH CQI Wideband Mode 1-0Mode 1-1 feedback (wideband CQI) type UE selective Mode 2-0 Mode 2-1(subband CQI)

A UE may be set in transmission modes as shown in Table 7. Referring toTable 7, in Mode 2-0 and Mode 2-1, a bandwidth part (BP) may be a set ofsubbands consecutively positioned in the frequency domain, and cover thesystem band or a designated band (set S). In Table 9, the size of eachsubband, the size of a BP and the number of BPs may depend on the sizeof the system band. In addition, the UE transmits CQIs for respectiveBPs in ascending order in the frequency domain so as to cover the systemband or designated band (set S).

The UE may have the following PUCCH transmission types according to atransmission combination of CQI/PMI/PTI/RI.

i) Type 1: the UE transmits a subband (SB) CQI of Mode 2-0 and Mode 2-1.

ii) Type 1a: the UE transmits an SB CQI and a second PMI.

iii) Types 2, 2b and 2c: the UE transmits a WB-CQI/PMI.

iv) Type 2a: the UE transmits a WB PMI.

v) Type 3: the UE transmits an RI.

vi) Type 4: the UE transmits a WB CQI.

vii) Type 5: the UE transmits an RI and a WB PMI.

viii) Type 6: the UE transmits an RI and a PTI.

When the UE transmits an RI and a WB CQI/PMI, the CQI/PMI aretransmitted in subframes having different periodicities and offsets. Ifthe RI needs to be transmitted in the same subframe as the WB CQI/PMI,the CQI/PMI are not transmitted.

Aperiodic CSI Request

Currently, the LTE standard uses the 2-bit CSI request field in DCIformat 0 or 4 to operate aperiodic CSI feedback when considering acarrier aggregation (CA) environment. When the UE is configured withseveral serving cells in the CA environment, the CSI request field isinterpreted as two bits. If one of the TMs 1 through 9 is set for allCCs (Component Carriers), aperiodic CSI feedback is triggered accordingto the values in Table 8 below, and TM 10 for at least one of the CCs Ifset, aperiodic CSI feedback is triggered according to the values inTable 9 below.

TABLE 8 A value of CSI request field Description ‘00’ No aperiodic CSIreport is triggered ‘01’ Aperiodic CSI report is triggered for a servingcell ‘10’ Aperiodic CSI report is triggered for a first group of servingcells configured by a higher layer ‘11’ Aperiodic CSI report istriggered for a second group of serving cells configured by a higherlayer

TABLE 9 A value of CSI request field Description ‘00’ No aperiodic CSIreport is triggered ‘01’ Aperiodic CSI report is triggered for a CSIprocess group configured by a higher layer for a serving cell ‘10’Aperiodic CSI report is triggered for a first group of CSI processesconfigured by a higher layer ‘11’ Aperiodic CSI report is triggered fora second group of CSI processes configured by a higher layer

In a wireless cellular communication system, one base station controlsdata transmission and reception for a plurality of user equipments(UEs), and scheduling information on downlink data, for example,time/frequency information for data transmission and MCS (modulation andcoding scheme) and HARQ (hybrid automatic retransmission request)related information are transmitted to a corresponding UE to allow theUE to receive data. Similarly, the base station notifies thecorresponding UE of uplink scheduling information to allow the UE totransmit uplink data. Recently, CA (carrier aggregation) fortransmitting downlink data to a single UE by aggregating unit componentcarrier (CC) has been considered to support a wider bandwidth whileusing band identification of the related art. Particularly, in the LTEstandard, self-carrier scheduling and cross-carrier scheduling have beenconsidered. In the self-carrier scheduling, each of a plurality of CCstransmits a control channel having scheduling information in a statethat a plurality of CCs of different duplex modes or the same duplexmode are aggregated. In the cross-carrier scheduling, one of theplurality of CCs transmits a control channel having schedulinginformation of another CC. In the current LTE standard, CA fortransmitting downlink data by aggregating 5 CCs has been considered.However, CA enhancement for transmitting downlink data by aggregating 5or more CCs (for example, 8 or 16 CCs) is recently considered to supporttraffic load which is rapidly increased.

In the present invention, in a state that a plurality of CC (componentcarriers) of different duplex modes or the same duplex mode areaggregated, a method for transmitting aperiodic CSI feedback will besuggested.

Hereinafter, for convenience of description, the suggested method willbe described based on the 3GPP LTE system. However, a range of thesystem to which the suggested method is applied may be applied toanother system (for example, UTRA, etc.) in addition to the 3GPP LTEsystem.

According to the current LTE standard, if the following condition issatisfied, there is no transport block for uplink shared channel(UL-SCH), and the UE transmits only a feedback of uplink controlinformation in a PUSCH reporting mode which is previously set. Forconvenience of description, UCI (uplink control information)transmission through PUSCH without UL-SCH will be referred to as “UCIonly PUSCH feedback”.

-   -   When DCI format 0 is used, 1_MCS=29 or DCI format 4 is used,        only one transport block (TB) is enabled and 1_MCS=29 of the TB,        and the number of transmission layer is 1,    -   CSI request bit field is 1 bit, aperiodic CSI report is        triggered, and N_PRB is 4 or less,    -   or, CSI request bit field is 2 bits, aperiodic CSI report is        triggered for one serving cell, and N_PRB is 4 or less,    -   or, CSI request bit field is 2 bits, aperiodic CSI report is        triggered for a plurality of serving cells, and N_PRB is 20 or        less,    -   or, CSI request bit field is 2 bits, aperiodic CSI report is        triggered for one CSI process, and N_PRB is 4 or less,    -   or, CSI request bit field is 2 bits, aperiodic CSI report is        triggered for a plurality of CSI processes, and N_PRB is 20 or        less.

First Alternative, Condition for UCI Only PUSCH Feedback

If the number of all CCs/CSI processes configured for the UE is apreviously defined value (or value configured through a higher layersignal) or more, or the number (for example, the number of CCs/CSIprocesses belonging to a first set indicated by a state ‘01’ of Table 8or Table 9) of CCs/CSI processes associated with a state of an aperiodicCSI request bit within UL grant DCI is a previously defined value (orvalue configured through a higher layer signal), UCI only PUSCH feedbackmay be configured when the following conditions are satisfied.

1-1th Condition

When DCI format 0 is used, 1_MCS=29 or DCI format 4 is used, only onetransport block (TB) is enabled and 1_MCS=29 of the TB, and the numberof transmission layer is 1,

{circle around (1)} CSI request bit field is 1 bit, aperiodic CSI reportis triggered, and N_PRB is 4 or less,

{circle around (2)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for one serving cell, and N_PRB is 4 or less,

{circle around (3)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for two to five serving cells, and N_PRB is 20 orless,

{circle around (4)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for 6 or more serving cells, and N_PRB is 4 or less,

{circle around (5)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for one CSI process, and N_PRB is 20 or less,

{circle around (6)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for two to five CSI processes, and N_PRB is 20 orless,

{circle around (7)} or, CSI request bit field is 2 bits, and aperiodicCSI report is triggered for 6 or more CSI processes,

UCI only PUSCH feedback is configured.

1-2th Condition

When DCI format 0 is used, 1_MCS=29 or DCI format 4 is used, only onetransport block (TB) is enabled and 1_MCS=29 of the TB, and the numberof transmission layer is 1,

{circle around (1)} CSI request bit field is 1 bit, aperiodic CSI reportis triggered, and N_PRB is 4 or less,

{circle around (2)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for one serving cell, and N_PRB is 4 or less,

{circle around (3)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for two to five serving cells, and N_PRB is 20 orless,

{circle around (4)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for 6 or more serving cells, and N_PRB is r or less,

{circle around (5)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for one CSI process, and N_PRB is 4 or less.

{circle around (6)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for two to five CSI processes, and N_PRB is 20 orless,

{circle around (7)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for 6 or more CSI processes, and N_PRB is r or less,

UCI only PUSCH feedback is configured.

1-3th Condition

When DCI format 0 is used, 1_MCS=29 or DCI format 4 is used, only onetransport block (TB) is enabled and 1_MCS=29 of the TB, and the numberof transmission layer is 1,

{circle around (1)} CSI request bit field is 1 bit, aperiodic CSI reportis triggered, and N_PRB is 4 or less,

{circle around (2)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for one serving cell, and N_PRB is 4 or less,

{circle around (3)} or, CSI request bit field is 2 bits, and aperiodicCSI report is triggered for two or more serving cells,

{circle around (4)} or, CSI request bit field is 2 bits, aperiodic CSIreport is triggered for one CSI process, and N_PRB is 4 or less,

{circle around (5)} or, CSI request bit field is 2 bits, and aperiodicCSI report is triggered for two or more CSI processes,

UCI only PUSCH feedback is configured.

In this case, r is a value previously defined or configured through ahigher layer, and, for example, may be configured in proportional to amaximum value of the number of all CCs/CSI processes configured for theUE, the number of CCs/CSI processes associated with a specific state ofan aperiodic CSI request bit within UL grant DCI, or the number ofCCs/CSI processes associated with each state of an aperiodic CSI requestbit within UL grant DCI. Alternatively, r may be configured dynamicallyin proportional to the number of CCs/CSI processes associated with atriggered state.

Second Alternative

As another embodiment, UCI only PUSCH feedback condition may beconfigured differently for a case that the number of all CCs/CSIprocesses configured for the UE or the number of CCs/CSI processesassociated with a state of an aperiodic CSI request bit within UL grantDCI is a predefined value (or value configured through a higher layersignal) or less and a case that the number of all CCs/CSI or the numberof CCs/CSI processes associated with the state exceeds the predefinedvalue.

2-1th Condition

When the number of all CCs/CSI processes configured for the UE or thenumber of CCs/CSI processes associated with a state of an aperiodic CSIrequest bit within UL grant DCI is NCC or less, DCI format 0 is used,I_MCS=29 or DCI format 4 is used, 1 transport block (TB) is onlyenabled, I_MCS=29 of the TB and the number of transmission layer is 1,

{circle around (1)} if CSI request bit field is 1 bit, aperiodic CSIreport is triggered and N_PRB is 4 or less,

{circle around (2)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one serving cell, and N_PRB is 4 or less,

{circle around (3)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for a plurality of serving cells, and N_PRB is20 or less,

{circle around (4)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one CSI process, and N_PRB is 4 or less,

{circle around (5)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for a plurality of CSI processes, and N_PRB is20 or less,

UCI only PUSCH feedback is configured.

Alternatively, when the number of all CCs/CSI processes configured forthe UE or the number of CCs/CSI processes associated with a state of anaperiodic CSI request bit within UL grant DCI exceeds NCC, DCI format 0is used, I_MCS=29 or DCI format 4 is used, 1 transport block (TB) isonly enabled, I_MCS=29 of the TB and the number of transmission layer is1,

{circle around (1)} if CSI request bit field is 1 bit, aperiodic CSIreport is triggered and N_PRB is 4 or less,

{circle around (2)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one serving cell, and N_PRB is 4 or less,

{circle around (3)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for a plurality of serving cells, and N_PRB is20 or less,

{circle around (4)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one CSI process, and N_PRB is 4 or less,

{circle around (5)} or, if CSI request bit field is 2 bits, andaperiodic CSI report is triggered for a plurality of CSI processes,

UCI only PUSCH feedback is configured.

2-2th Condition

When the number of all CCs/CSI processes configured for the UE or thenumber of CCs/CSI processes associated with a state of an aperiodic CSIrequest bit within UL grant DCI is NCC or less, DCI format 0 is used,I_MCS=29 or DCI format 4 is used, 1 transport block (TB) is onlyenabled, I_MCS=29 of the TB and the number of transmitting layers is 1,

{circle around (1)} if CSI request bit field is 1 bit, aperiodic CSIreport is triggered and N_PRB is 4 or less,

{circle around (2)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one serving cell, and N_PRB is 4 or less,

{circle around (3)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for a plurality of serving cells, and N_PRB is20 or less,

{circle around (4)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one CSI process, and N_PRB is 4 or less,

{circle around (5)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for a plurality of CSI processes, and N_PRB is20 or less,

UCI only PUSCH feedback is configured.

When the number of all CCs/CSI processes configured for the UE or thenumber of CCs/CSI processes associated with a state of an aperiodic CSIrequest bit within UL grant DCI exceeds NCC, DCI format 0 is used,I_MCS=29 or DCI format 4 is used, 1 transport block (TB) is onlyenabled, I_MCS=29 of the TB and the number of transmission layer is 1,

{circle around (1)} if CSI request bit field is 1 bit, aperiodic CSIreport is triggered and N_PRB is 4 or less,

{circle around (2)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one serving cell, and N_PRB is 4 or less,

{circle around (3)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for a plurality of serving cells, and N_PRB is ror less,

{circle around (4)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for one CSI process, and N_PRB is 4 or less,

{circle around (5)} or, if CSI request bit field is 2 bits, aperiodicCSI report is triggered for a plurality of CSI processes, and N_PRB is ror less,

UCI only PUSCH feedback is configured.

In this case, r is a value previously defined or configured through ahigher layer, and, for example, may be configured in proportional to amaximum value of the number of all CCs/CSI processes configured for theUE, the number of CCs/CSI processes associated with a specific state ofan aperiodic CSI request bit within UL grant DCI, or the number ofCCs/CSI processes associated with each state of an aperiodic CSI requestbit within UL grant DCI. Alternatively, r may be configured dynamicallyin proportional to the number of CCs/CSI processes associated with atriggered state.

In the above suggestion, the serving cell may mean (1) a cell configuredfor the UE, (2) a cell activated at a CSI request timing, or (3) a cellbased on an unlicensed band belonging to RRP at a CSI request timing.

Third Alternative

The number of CSI request bits in the first alternative or the secondalternative may be replaced with a predefined value (or value setthrough a higher layer signal) in addition to 1 or 2.

Fourth Alternative

If I_MCS of UL grant DCI is 30 or 31, CSI measurement target CCs or CSIprocesses of aperiodic CSI may also be configured differently.

If I_MCS of UL grant DCI is 30 or 31, RB condition for configuring UCIonly PUSCH feedback may also be defined differently from the existingcondition.

Fifth Alternative

If a modulation order in addition to QPSK is accepted for UCI only PUSCHfeedback, UCI only transmission condition may be configured differentlyfrom the existing condition. For example, if UCI only PUSCH istransmitted by 16QAM, RBs (for example, 2 RBs) smaller than the existingRBs may be configured for a trigger condition.

Sixth Alternative, Modulation Order for Feedback of Aperiodic CSI Only

6-1th Alternative

A modulation order of aperiodic CSI which will be transmitted by UCIonly PUSCH feedback may be configured differently by UL grant DCI thatincludes a trigger of aperiodic CSI. In more detail, a modulation orderof aperiodic CSI which will be transmitted by UCI only PUSCH feedbackmay be configured differently in accordance with a specific MCS index ofUL grant DCI (having non-zero RV (redundancy version)) that includes atrigger of aperiodic CSI and/or DMRS cyclic shift (combination). Forexample, in case of I_MCS=29, a modulation order of PUSCH may beconfigured by QPSK, and in case of I_MCS=30, a modulation order of PUSCHmay be configured by 16 QAM.

6-2th Alternative

A modulation order of aperiodic CSI which will be transmitted by UCIonly PUSCH feedback may be configured differently in accordance withresource amount (for example, the number of RBs allocated for PUSCH, orthe number of REs). For example, if the number of PUSCH scheduling RBsof aperiodic CSI for a plurality of CCs/CSI processes is N_P or less, amodulation order of aperiodic CSI which will be transmitted by UCI onlyPUSCH feedback may be configured by 16 QAM, and if the number of PUSCHscheduling RBs of aperiodic CSI for a plurality of CCs/CSI processesexceeds N_P, the modulation order may be configured by QPSK.

6-3th Alternative

A modulation order of aperiodic CSI which will be transmitted by UCIonly PUSCH feedback may be configured differently in accordance withcombination of the number of CSI measurement target CSI processes/CCs oftriggered aperiodic CSI and resource amount (for example, the number ofRBs allocated for PUSCH, or the number of available REs) allocated forPUSCH.

6-4th Alternative

A modulation order of aperiodic CSI which will be transmitted by UCIonly PUSCH feedback may be configured differently in accordance withcombination of feedback amount corresponding to aperiodic CSI andresource amount (for example, the number of RBs allocated for PUSCH, orthe number of available REs) allocated for PUSCH.

-   -   The modulation order is determined differently depending on a        coding rate calculated by combination of maximum CSI feedback        amount in the worst case of all RI cases and the allocated PUSCH        resource amount.    -   It may be considered that the CSI feedback includes RI, and it        may be considered that the PUSCH resource includes RI        transmission RE.    -   In this case, the same modulation order as that of another CSI        may be applied to RI.    -   The modulation order is determined differently depending on a        coding rate calculated by combination of CSI feedback amount        determined as a result of decoding of RI and the allocated PUSCH        resource amount.    -   It may be considered that the CSI feedback excludes RI, and it        may be considered that the PUSCH resource excludes RI        transmission RE.    -   In this case, a fixed low specific modulation order (for        example, QPSK) may be applied to RI.    -   It may be considered that the PUSCH resource excludes or        includes HARQ-ACK transmission RE. As another method, it may be        considered that the PUSCH resource excludes RE corresponding to        corresponding HARQ-ACK on the assumption that there is always        HARQ-ACK (that is, piggyback) transmission (regardless of the        presence of actual transmission) or always includes RE        corresponding to HARQ-ACK (regardless of the presence of actual        transmission).    -   Additionally, a fixed low specific modulation order (for        example, QPSK) may be applied to HARQ-ACK, or the same        modulation order as that of RI may be applied to HARQ-ACK, or        the same modulation order as that of another CSI (excluding RI)        may be applied to HARQ-ACK.

6-5th Alternative

A modulation order of aperiodic CSI which will be transmitted by UCIonly PUSCH feedback may be configured differently in accordance with thenumber of transmission layers.

For example, if a field of “precoding information and number of layers”on a received DCI format indicates the number of predefined (orsignaled) transmission layers or ‘the number of transmission layers’more than the predefined transmission layers, the modulation order ofaperiodic CSI which will be transmitted by UCI only PUSCH feedback maybe configured differently from the existing case.

For another example, if a field of “precoding information and number oflayers” on a received DCI format indicates ‘reverse state’ (on thecurrent LTE standard), the modulation order of aperiodic CSI which willbe transmitted by UCI only PUSCH feedback may be configured differentlyfrom the existing case. At this time, for example, TPMI (transmitprecoding matrix indicator) information indicated by ‘reserved state’and/or information on ‘the number of transmission layers’ may benotified from an eNB to a UE through predefined signaling, or maypreviously be scheduled and fixed.

6-6th Alternative

A modulation order of aperiodic CSI which will be transmitted by UCIonly PUSCH feedback may be configured differently in accordance with aDCI format of UL grant DCI that includes a trigger of aperiodic CSI.

For another example, the modulation order of aperiodic CSI which will betransmitted by UCI only PUSCH feedback may be configured differently inaccordance with combination of DCI format and MCS index of UL grant DCIthat includes a trigger of aperiodic CSI, the enable number of transportblocks, and/or ‘the number of transmission layers’.

6-7th Alternative

If a large number of cells greater than a predefined (or signaled)threshold value are configured by CA (carrier aggregation) (or ifmassive CA is configured), a modulation order of aperiodic CSI whichwill be transmitted by UCI only PUSCH feedback may be configureddifferently from the existing rule. For example, the correspondingthreshold value may be set to 5.

6-8th Alternative

A modulation order of aperiodic CSI which will be transmitted by UCIonly PUSCH feedback may be configured differently in accordance with thenumber of bits of a “CSI request” field on a received DCI format. Forexample, if the “CSI request” field is 2 bits or less, the modulationorder of aperiodic CSI which will be transmitted by UCI only PUSCHfeedback may be configured by QPSK, and if the “CSI request” field is 3bits or more, the modulation order of aperiodic CSI which will betransmitted by UCI only PUSCH feedback may be configured by 16QAM.

6-9th Alternative

A modulation order of (1) aperiodic CSI measurement target (DL) CC orCSI process set and a modulation order of (2) PUSCH may be linkedtogether and configured per state corresponding to a CSI request bitthrough a higher layer signal (for example, RRC signaling). For example,it is assumed that QPSK is linked to a specific state ‘X’ and if 16QAMis linked to another specific state ‘Y’. If the state ‘X’ is triggered,the modulation order of aperiodic CSI is configured by QPSK, whereby UCIonly PUSCH feedback may be transmitted. If the state ‘Y’ is triggered,the modulation order of aperiodic CSI is configured by 16QAM, wherebyUCI only PUSCH feedback may be transmitted.

In the above all of the schemes, CSI feedback amount may be consideredas the number of CSI processes or the number of CSI bits, and the PUSCHresource amount may be considered as the number of RBs or the number ofavailable REs.

6-10th Alternative

In association with the 6-1th alternative, the number of CSI measurementtarget CCs/CSI processes that may be associated with each stateindicated by the CSI request bit may be configured differently inaccordance with I_MCS of received UL grant DCI. For example, in case ofI_MCS=29, a modulation order of A-CSI only feedback is QPSK, and 10CCs/CSI processes are associated with each state. On the contrary, incase of I_MCS=30, the modulation order of A-CSI only feedback is 16QAM,and at this time, 5 CCs/CSI processes are associated with each state.However, the above rule may be limited to a case that a certain numberof CCs or more are configured for the UE or a certain number of CSIprocesses or more are configured for the UE.

6-11th Alternative

The number of CSI measurement target CCs/CSI processes that may beassociated with each state indicated by the CSI request bit may beconfigured differently in accordance with a state of “precodinginformation and number of layers” on a DCI format. However, the aboverule may be limited to a case that a certain number of CCs or more areconfigured for the UE or a certain number of CSI processes or more areconfigured for the UE.

6-12th Alternative

The number of CSI measurement target CCs/CSI processes that may beassociated with each state indicated by the CSI request bit may beconfigured differently in accordance with a DCI format of UL grant DCIthat includes a trigger of aperiodic CSI. However, the above rule may belimited to a case that a certain number of CCs or more are configuredfor the UE or a certain number of CSI processes or more are configuredfor the UE.

In all the proposals suggested in the sixth alternative of the presentinvention, a rule may be determined such that the modulation order ofaperiodic CSI which will be transmitted by UCI only PUSCH feedback maybe configured differently from the existing case by combination withcondition(s) that (1) the number of all CCs/CSI processes configured forthe UE is a certain threshold value or more/less or (2) the number ofaperiodic CSI measurement target (DL) CCs/CSI processes associated witha specific state of the CSI request bit within UL grant DCI is a certainthreshold value or more/less.

In all the proposals of the present invention, (CSI report target) DLCCs/cells and CSI processes may be applied by being mutually replacedwith each other.

Seventh Alternative, Modulation Order Per UCI Content (A/N, RIProtection)

If UCI only PUSCH feedback is configured, a modulation order may beconfigured differently per UCI content by a rule which is previouslydefined, and may be mapped into UCI RE. In more detail, a UE may performmapping by always configuring the modulation order for a specific UCI(for example, HARQ-ACK, RI) as QPSK (or specific modulation order whichis previously scheduled), and may perform mapping by configuring themodulation order for the other CSI (for example, PMI, CQI) as QPSK or16QAM (or another modulation order) in accordance with theaforementioned alternative or other scheme.

Alternatively, (1) if the number of all CCs/CSI processes configured forthe UE is a certain threshold value or more/less or (2) the number ofaperiodic CSI measurement target (DL) CCs/CSI processes associated witha specific state of the CSI request bit within UL grant DCI is a certainthreshold value or more/less, and if UCI only PUSCH feedback isconfigured, the modulation order may be configured differently per UCIcontent in accordance with a predefined rule as suggested above and maybe mapped into UCI RE.

Eighth Alternative, New Interpretation of DCI Field

If the aforementioned condition for UCI only PUSCH feedback according tothe current LTE standard is satisfied and therefore UCI only PUSCHfeedback is configured, a new data indicator (NDI) field within DCI maypreviously be defined to indicate a modulation order of UCI content. Forexample, if UCI only PUSCH feedback is configured and NDI=0, UCI contentmay be configured as QPSK and if NDI=1, may be configured as 16QAM.Alternatively, if MCS index of corresponding UL grant DCI corresponds toa specific value (for example, I_MCS>=29), the NDI field within DCI maypreviously be defined to indicate the modulation order of UCI content.Alternatively, (1) if the number of all CCs/CSI processes configured forthe UE is a certain threshold value or more/less or (2) the number ofaperiodic CSI measurement target (DL) CCs/CSI processes associated witha specific state of the CSI request bit within UL grant DCI is a certainthreshold value or more/less, and if UCI only PUSCH feedback isconfigured, the NDI field may previously be defined to indicate themodulation order of UCI content

As another method, if the aforementioned condition for UCI only PUSCHfeedback according to the current LTE standard is satisfied andtherefore UCI only PUSCH feedback is configured, a specific state foraperiodic CSI may be indicated by combination of the NDI field withinDCI and the CSI request bit field. Alternatively, if MCS index ofcorresponding UL grant DCI corresponds to a specific value (for example,I_MCS>=29), the specific state for aperiodic CSI may be indicated bycombination of the NDI field within DCI and the CSI request field.Alternatively, (1) if the number of all CCs/CSI processes configured forthe UE is a certain threshold value or more/less or (2) the number ofaperiodic CSI measurement target (DL) CCs/CSI processes associated witha specific state of the CSI request bit within UL grant DCI is a certainthreshold value or more/less, and if UCI only PUSCH feedback isconfigured, the specific state for aperiodic CSI may be indicated bycombination of the NDI field and the CSI request field.

Since the examples of the above-described suggestions may be included asone of the implementation methods of the present invention, it will beapparent that the examples may be regarded as the suggested methods.Also, although the above-described suggestions may be implementedindependently, the suggestions may be implemented in the form ofcombination (or incorporation) of some of the suggested methods. A rulemay be defined such that information as to application of the suggestedmethods (or information on the rules of the suggested methods) may benotified from the eNB to the UE through a predefined signal (e.g.,physical layer signal or higher layer signal).

FIG. 5 is a diagram illustrating an operation according to oneembodiment of the present invention.

FIG. 5 relates to a method for reporting an aperiodic channel state in awireless communication system.

The UE 51 may receive an aperiodic CSI (channel state information)report request from the eNB 52 (S510). The UE may compute aperiodic CSIcorresponding to the aperiodic CSI report request and transmit theaperiodic CSI to the eNB through an uplink shared channel (S530). Inthis case, the uplink shared channel may include a physical uplinkshared channel. If the number of component carriers or CSI processes forthe UE exceeds a specific value, only uplink control information thatincludes the aperiodic CSI may be transmitted through the uplink sharedchannel under a specific condition. That is, the uplink shared channelmay be used to transmit the uplink control information only withoutuplink data.

The specific condition may include a case that DCI (downlink controlinformation) format 0 is used for the aperiodic CSI report request and amodulation and coding scheme field value included in the DCI is 29.

Or, the specific condition may include a case that DCI format 4 is usedfor the aperiodic CSI report request, only one TB is enabled, amodulation and coding scheme field value included in the DCI is 29, andthe number of transmission layers is 1.

Or, the specific condition may include a case that a field for theaperiodic CSI report request is N bits, the aperiodic CSI report istriggered, and the number of resource blocks is 4 or less.

Or, the specific condition may include a case that a field for theaperiodic CSI report request is N+1 bits, the aperiodic CSI report istriggered for one serving cell, and the number of resource blocks is 4or less.

Or, the specific condition may include a case that a field for theaperiodic CSI report request is N+1 bits, and the aperiodic CSI reportis triggered for a plurality of cells.

Or, the specific condition may include a case that a field for theaperiodic CSI report request is N+1 bits, the aperiodic CSI report istriggered for one CSI process, and the number of resource blocks is 4 orless.

Or, the specific condition may include a case that a field for theaperiodic CSI report request is N+1 bits and the aperiodic CSI report istriggered for a plurality of CSI processes.

Also, a modulation order of the aperiodic CSI may be determined inaccordance with at least one parameter related to DCI for the aperiodicCSI report request.

Or, the modulation order of the aperiodic CSI may be determined inaccordance with a resource size allocated for the uplink shared channel.

Or, the modulation order of the aperiodic CSI may be determined inaccordance with combination of the number of component carriers or CSIprocesses for the aperiodic CSI and a resource size allocated for theuplink shared channel.

Or, the modulation order of the aperiodic CSI may be determined inaccordance with combination of a size of the aperiodic CSI and aresource size allocated for the uplink shared channel.

Or, the modulation order of the aperiodic CSI may be determined inaccordance with the number of transmission layers included in DCI forthe aperiodic CSI report request.

Or, the modulation order of the aperiodic CSI may be determined inaccordance with a format of DCI for the aperiodic CSI report request.

Or, the modulation order of the aperiodic CSI may be determined inaccordance with the number of bits of the field for the aperiodic CSIreport request.

Or, the modulation order of the aperiodic CSI may be determined inaccordance with a bit value of the field for the aperiodic CSI reportrequest.

Although the embodiments according to the present invention have beenbriefly described with reference to FIG. 5, the embodiment related toFIG. 5 may include at least a part of the aforementioned embodiment(s)alternatively or additionally.

FIG. 6 is a block diagram illustrating a transmitter 10 and a receiver20 configured to implement embodiments of the present invention. Each ofthe transmitter 10 and receiver 20 includes a radio frequency (RF) unit13, 23 capable of transmitting or receiving a radio signal that carriesinformation and/or data, a signal, a message, etc., a memory 12, 22configured to store various kinds of information related tocommunication with a wireless communication system, and a processor 11,21 operatively connected to elements such as the RF unit 13, 23 and thememory 12, 22 to control the memory 12, 22 and/or the RF unit 13, 23 toallow the device to implement at least one of the embodiments of thepresent invention described above.

The memory 12, 22 may store a program for processing and controlling theprocessor 11, 21, and temporarily store input/output information. Thememory 12, 22 may also be utilized as a buffer. The processor 11, 21controls overall operations of various modules in the transmitter or thereceiver. Particularly, the processor 11, 21 may perform various controlfunctions for implementation of the present invention. The processors 11and 21 may be referred to as controllers, microcontrollers,microprocessors, microcomputers, or the like. The processors 11 and 21may be achieved by hardware, firmware, software, or a combinationthereof. In a hardware configuration for an embodiment of the presentinvention, the processor 11, 21 may be provided with applicationspecific integrated circuits (ASICs) or digital signal processors(DSPs), digital signal processing devices (DSPDs), programmable logicdevices (PLDs), and field programmable gate arrays (FPGAs) that areconfigured to implement the present invention. In the case which thepresent invention is implemented using firmware or software, thefirmware or software may be provided with a module, a procedure, afunction, or the like which performs the functions or operations of thepresent invention. The firmware or software configured to implement thepresent invention may be provided in the processor 11, 21 or stored inthe memory 12, 22 to be driven by the processor 11, 21.

The processor 11 of the transmitter 10 performs predetermined coding andmodulation of a signal and/or data scheduled by the processor 11 or ascheduler connected to the processor 11, and then transmits a signaland/or data to the RF unit 13. For example, the processor 11 converts adata sequence to be transmitted into K layers through demultiplexing andchannel coding, scrambling, and modulation. The coded data sequence isreferred to as a codeword, and is equivalent to a transport block whichis a data block provided by the MAC layer. One transport block is codedas one codeword, and each codeword is transmitted to the receiver in theform of one or more layers. To perform frequency-up transformation, theRF unit 13 may include an oscillator. The RF unit 13 may include Nttransmit antennas (wherein Nt is a positive integer greater than orequal to 1).

The signal processing procedure in the receiver 20 is configured as areverse procedure of the signal processing procedure in the transmitter10. The RF unit 23 of the receiver 20 receives a radio signaltransmitted from the transmitter 10 under control of the processor 21.The RF unit 23 may include Nr receive antennas, and retrieves basebandsignals by frequency down-converting the signals received through thereceive antennas. The RF unit 23 may include an oscillator to performfrequency down-converting. The processor 21 may perform decoding anddemodulation on the radio signal received through the receive antennas,thereby retrieving data that the transmitter 10 has originally intendedto transmit

The RF unit 13, 23 includes one or more antennas. According to anembodiment of the present invention, the antennas function to transmitsignals processed by the RF unit 13, 23 are to receive radio signals anddeliver the same to the RF unit 13, 23. The antennas are also calledantenna ports. Each antenna may correspond to one physical antenna or beconfigured by a combination of two or more physical antenna elements. Asignal transmitted through each antenna cannot be decomposed by thereceiver 20 anymore. A reference signal (RS) transmitted in accordancewith a corresponding antenna defines an antenna from the perspective ofthe receiver 20, enables the receiver 20 to perform channel estimationon the antenna irrespective of whether the channel is a single radiochannel from one physical antenna or a composite channel from aplurality of physical antenna elements including the antenna. That is,an antenna is defined such that a channel for delivering a symbol on theantenna is derived from a channel for delivering another symbol on thesame antenna. An RF unit supporting the Multiple-Input Multiple-Output(MIMO) for transmitting and receiving data using a plurality of antennasmay be connected to two or more antennas.

In embodiments of the present invention, the UE operates as thetransmitter 10 on uplink, and operates as the receiver 20 on downlink.In embodiments of the present invention, the eNB operates as thereceiver 20 on uplink, and operates as the transmitter 10 on downlink.

The transmitter and/or receiver may be implemented by one or moreembodiments of the present invention among the embodiments describedabove.

Detailed descriptions of preferred embodiments of the present inventionhave been given to allow those skilled in the art to implement andpractice the present invention. Although descriptions have been given ofthe preferred embodiments of the present invention, it will be apparentto those skilled in the art that various modifications and variationscan be made in the present invention defined in the appended claims.Thus, the present invention is not intended to be limited to theembodiments described herein, but is intended to have the widest scopeconsistent with the principles and novel features disclosed herein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wireless communication devicessuch as a terminal, a relay, and a base station.

The invention claimed is:
 1. A method for reporting, by a user equipment(UE), channel state information (CSI) in a wireless communicationsystem, the method comprising: receiving uplink (UL) grant downlinkcontrol information (DCI) which includes a CSI request field fortriggering an aperiodic CSI report on a set of CSI processes, andinformation on a modulation and coding scheme (MCS) index, and resourceblock information for a physical uplink shared channel (PUSCH); andtransmitting uplink control information (UCI) including the aperiodicCSI report through the PUSCH based on the UL grant DCI, wherein only theUCI is transmitted with no uplink shared channel (UL-SCH) through thePUSCH when: the UL grant DCI is received in DCI format 0 and the MCSindex is 29; or the UL grant DCI is received in DCI format 4, only 1transport block (TB) is enabled by the UL grant DCI, the MCS index forthe enabled TB is 29, and the number of transmission layers based on theUL grant DCI is 1, the number of bits for the CSI request field is aninteger larger than 1, and the number of CSI processes for which theaperiodic CSI report is triggered exceeds
 5. 2. The method according toclaim 1, wherein the number of bits for the CSI request field is apositive integer other than 1 or
 2. 3. The method according to claim 1,wherein only the UCI is transmitted with no UL-SCH through the PUSCH,irrespective of the number of resource blocks allocated by the resourceblock information, when: the UL grant DCI is received in DCI format 0and the MCS index is 29; or the UL grant DCI is received in DCI format4, only 1 TB is enabled by the UL grant DCI, the MCS index for theenabled TB is 29, and the number of transmission layers based on the ULgrant DCI is 1, the number of bits for the CSI request field is aninteger larger than 1, and the number of CSI processes for which theaperiodic CSI report is triggered exceeds
 5. 4. The method according toclaim 1, wherein only the UCI is transmitted with no UL-SCH through thePUSCH when: the UL grant DCI is received in DCI format 0 and the MCSindex is 29; or the UL grant DCI is received in DCI format 4, only 1 TBis enabled by the UL grant DCI, the MCS index for the enabled TB is 29,and the number of transmission layers based on the UL grant DCI is 1,the number of bits for the CSI request field is an integer larger than1, the number of CSI processes for which the aperiodic CSI report istriggered is 2 to 5, and the number of resource blocks allocated by theresource block information is less than or equal to
 20. 5. A userequipment (UE) for reporting channel state information (CSI) in awireless communication system, the UE comprising: a transmitter and areceiver; and a processor, operatively coupled to the transmitter andthe receiver, the processor configured to: control the receiver toreceive uplink (UL) grant downlink control information (DCI) whichincludes a CSI request field for triggering an aperiodic CSI report on aset of CSI processes, and information on a modulation and coding scheme(MCS) index, and resource block information for a physical uplink sharedchannel (PUSCH); and control the transmitter to transmit uplink controlinformation (UCI) including the aperiodic CSI report through the PUSCHbased on the UL grant DCI, wherein only the UCI is transmitted with nouplink shared channel (UL-SCH) through the PUSCH when: the UL grant DCIis received in DCI format 0 and the MCS index is 29; or the UL grant DCIis received in DCI format 4, only 1 transport block (TB) is enabled bythe UL grant DCI, the MCS index for the enabled TB is 29, and the numberof transmission layers based on the UL grant DCI is 1, the number ofbits for the CSI request field is an integer larger than 1, and thenumber of CSI processes for which the aperiodic CSI report is triggeredexceeds
 5. 6. The UE according to claim 5, wherein the number of bitsfor the CSI request field is a positive integer other than 1 or
 2. 7.The UE according to claim 5, wherein the processor is further configuredto control the transmitter to transmit only the UCI with no UL-SCHthrough the PUSCH, irrespective of the number of resource blocksallocated by the resource block information, when: the UL grant DCI isreceived in DCI format 0 and the MCS index is 29; or the UL grant DCI isreceived in DCI format 4, only 1 TB is enabled by the UL grant DCI, theMCS index for the enabled TB is 29, and the number of transmissionlayers based on the UL grant DCI is 1, the number of bits for the CSIrequest field is an integer larger than 1, and the number of CSIprocesses for which the aperiodic CSI report is triggered exceeds
 5. 8.The UE according to claim 5, wherein the processor is further configuredto control the transmitter to transmit only the UCI with no UL-SCHthrough the PUSCH when: the UL grant DCI is received in DCI format 0 andthe MCS index is 29; or the UL grant DCI is received in DCI format 4,only 1 TB is enabled by the UL grant DCI, the MCS index for the enabledTB is 29, and the number of transmission layers based on the UL grantDCI is 1, the number of bits for the CSI request field is an integerlarger than 1, the number of CSI processes for which the aperiodic CSIreport is triggered is 2 to 5, and the number of resource blocksallocated by the resource block information is less than or equal to 20.